Do you have a neutral line at the switch?
Some UK houses do and some do not.
Assuming you have L+N lines in the switch you can use one of these: https://www.itead.cc/smart-home/sonoff-t1.html
1, 2 and 3 gang available.
They can also be flashed with other firmware (Tasmota etc)
You can also DIY up some solutions - e.g. dimmer switch that I created:
If you only have L line in the switch box then your options are limited.
Probably only RF switches like lightwaverf will be possible, or placing sonoff by the ceiling rose as @Bobby_Nobble mentioned.